Large Prospective Cohort Study in England: 84% of Population Infected with SARS-CoV-2 Develop Immunity

Large Prospective Cohort Study in England 84% of Population Infected with SARS-CoV-2 Develop Immunity

A massive study in the United Kingdom hasn’t received much press attention across the Pond in America but perhaps should so. Perhaps the outcomes of the study serve to give hope, not succumbing to fear and uncertainty?   Led by Victoria Jane Hall with Public Health England Colindale, “the SARS-CoV-2 Immunity and Reinfection Evaluation study” involved the study of 30,625 subjects recruited from publicly funded hospitals across England. A large, multicenter prospective cohort study involved health care workers, support staff, and administrative support employed at public hospitals and whoever could remain involved in the study for up to 12 months. Published in The Lancet, the results are profound. At its core, the study sought to determine whether those individuals that have already been infected by SARS-CoV-2, the virus behind COVID-19 had decreased risk of reinfection. Put another way, does the body’s natural immune response protect from COVID-19? The answer is yes. As the authors declared in the prestigious peer review journal, while a previous history of COVID-19 infection means that according to these study results, the individual faces a 84% lower risk of future infection. The study data reveals a median protective effort observed seven months post primary infection. As seroconversions were precluded, this time period represents the minimum probable effect. The Public Health England Colindale study reveals that exposure to COVID-19 illness induces effective immunity to future infections in most individuals. Why haven’t these findings been widely reported in major media? Assuming these findings can be replicated in other populations, what’s the impact to public health policy in the age of COVID-19?

This fascinating study received next to no press coverage unfortunately. This seems odd, considering the implications for public health policy. What if this is repeatable across the North American continent—meaning that nearly 85% of those infected once build immunity? Would this not influence how vaccination strategy is employed?

The Study Methods

This large study excluded participants if they had no PCR tests post enrollment in the study, or if they enrolled after December 31, 2020 or had insufficient PCR and antibody data for cohort assignment as declared in The Lancet. The study participants were required to attend regular COVID-19 testing, each 2 to 4 weeks apart while also completing questionnaires every couple weeks covering symptoms and exposures.

Once enrolled, study participants got assigned to one of two cohorts—1) the positive cohort and 2) negative cohort. The positive cohort was the group involving those who were antibody positive, or had a previously positive antibody test. While the negative cohort were those that were deemed antibody negative, that is no previous positive PCR or antibody test.

The targeted outcome of interest was actual reinfection with the positive cohort or a primary infection in the negative cohort as determined by PCR tests. Should a study subject actually become reinfected, those cases were assigned to investigators and a study team for clinical review and classification based on case definitions, and as reported in The Lancet, “confirmed, probable, or possible, and symptom-status, depending on the hierarchy of evidence.”

A first positive PCR test was established for primary infections associated with the negative cohort while seroconversions were not included when associated with a positive PCR test. Employing a proportional hazards frailty model based on Poisson distribution, the team calculated incidence rate ratios (IRR) as part of the study effort to compare the infection status rates among the two cohorts.

Public Health England Merged into DHSC UK

This important and underreported study was led by Public Health England Colindale, an executive agency of the Department of Health and Social Care in the United Kingdom, which came into being on April 1, 2013 to protect and improve health and well being and reduce inequalities. Public Health England formed as part of the reorganization of the National Health Service (NHS) England as part of the Health and Social Care Act 2012. Then, interestingly, on April 1, 2021, Public Health England was replaced by the UK Health Security Agency, a new body formed to deal with the threat of infectious disease by combining Public Health England with NHS Test and Trace Operation. The operational autonomy once known for Public Health England was gone.

Lead Research/Investigator

Victoria Jane Hall, FFPH, Public Health England Colindale, National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance at the University of Oxford, University of Oxford, Corresponding Author

Other authors can be viewed here.

Call to Action: Check out the study results in The Lancet